
average number of rating

number of 1-star ratings, 2-star ratings, 3-star ratings, 4-star ratings, 5-star ratings

rating entropy

number of reviews received

Sentiment of the reviews: For each book, we concatenate all the reviews in one month and find out the fraction of positive sentiment words (positive sentiment score) and the fraction of negative sentiment words (negative sentiment score) by using MPQA sentiment lexicon [1]}. We use these two sentiment scores as two separate features.

Cognitive dimension of the reviews: There could be differences in the cognitive dimension (linguistic and psychological) for the two category of books. To quantify this, we consider Linguistic Inquiry and Word Count (LIWC) software [2]}. LIWC takes a text document as input and outputs a score for the input over all the categories based on the writing style and psychometric properties of the document.

